Getting started with Python on Compute Engine

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This tutorial shows how to get started with Compute Engine. Follow this tutorial by deploying a Hello World Python web app to Compute Engine. For help getting started with App Engine, see the App Engine standard environment.

Objectives

• Use Cloud Shell to download and deploy a Hello World sample app.
• Deploy a Hello World sample app to a single Compute Engine instance.

Costs

In this document, you use the following billable components of Google Cloud:

• Compute Engine

To generate a cost estimate based on your projected usage, use the pricing calculator. New Google Cloud users might be eligible for a free trial.

Before you begin

1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

2. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

   Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

   Go to project selector

3. Make sure that billing is enabled for your Google Cloud project.

4. Enable the Compute Engine API.

   Enable the API

5. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

   Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

   Go to project selector

6. Make sure that billing is enabled for your Google Cloud project.

7. Enable the Compute Engine API.

   Enable the API

8. In the Google Cloud console, open the app in Cloud Shell.

   Go to Cloud Shell

   Cloud Shell provides command-line access to your cloud resources directly from the browser.

9. If you agree to clone the repository, click Confirm to download the sample code and change into the app directory.

10. In Cloud Shell, configure the gcloud CLI to use your new Google Cloud project:

    # Configure gcloud for your project
    gcloud config set project YOUR_PROJECT_ID

Running the app in Cloud Shell

1. In Cloud Shell, install your app dependencies using pip:

   pip3 install -r requirements.txt --user
   

2. Install the Gunicorn HTTP server:

   pip3 install gunicorn --user
   

3. Run the Gunicorn HTTP server:

   ~/.local/bin/gunicorn -b :8080 main:app
   

4. In Cloud Shell, click Web preview , and select Preview on port 8080. This opens a new window with your running app.

5. To stop the local web server, press Control+C.

Deploying to a single instance

This section walks you through running a single instance of your app on Compute Engine.

From Cloud Shell, you can deploy to a single Compute Engine instance virtual machine (VM) which runs your app.

Use a startup script to initialize an instance

You need a way to instruct your instance to download and run your code. An instance can have a startup script that runs whenever the instance is started or restarted.

# Install or update needed software
apt-get update
apt-get install -yq git supervisor python python-pip python3-distutils
pip install --upgrade pip virtualenv

# Fetch source code
export HOME=/root
git clone https://github.com/GoogleCloudPlatform/getting-started-python.git /opt/app

# Install Cloud Ops Agent
sudo bash /opt/app/gce/add-google-cloud-ops-agent-repo.sh --also-install

# Account to own server process
useradd -m -d /home/pythonapp pythonapp

# Python environment setup
virtualenv -p python3 /opt/app/gce/env
/bin/bash -c "source /opt/app/gce/env/bin/activate"
/opt/app/gce/env/bin/pip install -r /opt/app/gce/requirements.txt

# Set ownership to newly created account
chown -R pythonapp:pythonapp /opt/app

# Put supervisor configuration in proper place
cp /opt/app/gce/python-app.conf /etc/supervisor/conf.d/python-app.conf

# Start service via supervisorctl
supervisorctl reread
supervisorctl update

The startup script performs these tasks:

• Installs Python 3 and Pip.

• Installs the Cloud Logging agent. The agent automatically collects logs from syslog.

• Installs Supervisor to run the app as a daemon.

• Clones the app's source code from the Cloud Source Repositories and installs dependencies.

• Configures Supervisor to run the app. Supervisor makes sure the app is restarted if it exits unexpectedly or is terminated by an admin or other process. It also sends the app's stdout and stderr to syslog to be collected by the Logging agent.

Create and configure a Compute Engine instance

1. Create a Compute Engine instance:

   Linux/macOS

   MY_INSTANCE_NAME="my-app-instance"
   ZONE=us-central1-a
   
   gcloud compute instances create $MY_INSTANCE_NAME \
       --image-family=debian-10 \
       --image-project=debian-cloud \
       --machine-type=g1-small \
       --scopes userinfo-email,cloud-platform \
       --metadata-from-file startup-script=startup-script.sh \
       --zone $ZONE \
       --tags http-server

   Windows

   gcloud compute instances create my-app-instance ^
       --image-family=debian-9 ^
       --image-project=debian-cloud ^
       --machine-type=g1-small ^
       --scopes userinfo-email,cloud-platform ^
       --metadata-from-file startup-script=gce/startup-script.sh ^
       --zone us-central1-f ^
       --tags http-server
   

   Replace the zone with a development zone, for example us-central1-a. For more information on regions and zones, see Geography and regions.

   This creates a new instance, allows it to access Google Cloud services, and runs your startup script. The instance name is my-app-instance.

2. Check the progress of the instance creation:

   gcloud compute instances get-serial-port-output my-app-instance --zone YOUR_ZONE
   

   Replace YOUR_ZONE with the zone you deployed your instance to.

   When the startup script is complete, you see the following message:

   startup-script: INFO Finished running startup scripts.
   

3. Create a firewall rule to allow traffic to your instance:

   gcloud compute firewall-rules create default-allow-http-8080 \
       --allow tcp:8080 \
       --source-ranges 0.0.0.0/0 \
       --target-tags http-server \
       --description "Allow port 8080 access to http-server"
   

4. Get the external IP address of your instance:

   gcloud compute instances list
   

5. To see your app running, enter this URL in your browser:

   http://YOUR_INSTANCE_IP:8080
   

   Replace YOUR_INSTANCE_IP with the external IP address of your instance.

Manage and monitor an instance

You can use the Google Cloud console to monitor and manage your instance.

1. In the Google Cloud console, go to the VM instances page.

   Go to VM instances

2. In the list of virtual machine instances, click SSH in the row of the instance that you want to connect to.

3. To view all of the logs generated by your Compute Engine resources, go to the Logs Explorer page.

   Go to Logs Explorer

   Cloud Logging is automatically configured to gather logs from various common services, including syslog.

Clean up

To avoid incurring charges to your Google Cloud account for the resources used in this tutorial, either delete the project that contains the resources, or keep the project and delete the individual resources.

Delete the project

Caution: Deleting a project has the following effects:

• Everything in the project is deleted. If you used an existing project for the tasks in this document, when you delete it, you also delete any other work you've done in the project.
• Custom project IDs are lost. When you created this project, you might have created a custom project ID that you want to use in the future. To preserve the URLs that use the project ID, such as an appspot.com URL, delete selected resources inside the project instead of deleting the whole project.

If you plan to explore multiple architectures, tutorials, or quickstarts, reusing projects can help you avoid exceeding project quota limits.

1. In the Google Cloud console, go to the Manage resources page.

   Go to Manage resources

2. In the project list, select the project that you want to delete, and then click Delete.
3. In the dialog, type the project ID, and then click Shut down to delete the project.

Delete the individual resources

gcloud compute instances delete my-app-instance --zone=YOUR_ZONE --delete-disks=all
gcloud compute firewall-rules delete default-allow-http-8080

What's next

• Create managed instance groups.
• Create a load balancer.
• Handle sessions with Firestore.
• Add background processing with Pub/Sub and Cloud Run.
• Deploy an app to Google Kubernetes Engine.
• Authenticate users with Identity-Aware Proxy.